<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>自动跳转首页</title>
    <style>
        p {
            text-align: center;
        }
        span {
            color:red;
        }
    </style>
</head>
<body>
    <p>
        <span id="time">5</span> 秒后自动跳转首页...
    </p>
    <script>
        var time = document.getElementById("time");
        var clock = 5;
        function showTime(){
            clock--;
            if(clock <= 0){
                location.href = "http://www.baidu.com";
            }
            time.innerHTML = clock;
        }
        setInterval(showTime, 1000);
    </script>
</body>
</html>